feat: implement needed helper methods

Author: janek26

__tests__/utils.test.ts

@@ -1,5 +1,5 @@
 import fs from 'fs';
-import { compressProgram, makeAddress, isBrowser, JsonParser } from '..';
+import { compressProgram, makeAddress, isBrowser, JsonParser, getSelectorFromName } from '../src';
 
 const compiledArgentAccount = JsonParser.parse(
   fs.readFileSync('./__mocks__/ArgentAccount.json').toString('ascii')
@@ -33,3 +33,15 @@ describe('makeAddress()', () => {
     expect(starkAddress).toBe('0xdfd0f27fce99b50909de0bdd328aed6eabe76bc5');
   });
 });
+describe('starknetKeccak()', () => {
+  test('hash works for value="test"', () => {
+    expect(getSelectorFromName('test')).toBe(
+      '0x22ff5f21f0b81b113e63f7db6da94fedef11b2119b4088b89664fb9a3cb658'
+    );
+  });
+  test('hash works for value="initialize"', () => {
+    expect(getSelectorFromName('initialize')).toBe(
+      '0x79dc0da7c54b95f10aa182ad0a46400db63156920adb65eca2654c0945a463'
+    );
+  });
+});

package-lock.json

@@ -56,6 +56,7 @@
   },
   "dependencies": {
     "axios": "^0.23.0",
+    "ethereum-cryptography": "^0.2.0",
     "json-bigint": "^1.0.0",
     "pako": "^2.0.4"
   },

package.json

@@ -1,12 +1,18 @@
 import { gzip } from 'pako';
 import Json from 'json-bigint';
+import { keccak256 } from 'ethereum-cryptography/keccak';
 import { CompressedProgram, Program } from './types';
 import { CONTRACT_ADDRESS_LOWER_BOUND, CONTRACT_ADDRESS_UPPER_BOUND } from './constants';
 
 export const isBrowser = typeof window !== 'undefined';
 
+export const arrayBufferToString = (array: ArrayBuffer): string =>
+  String.fromCharCode.apply(null, array as any);
+
+export const stringToUint8Array = (str: string): Uint8Array => new TextEncoder().encode(str);
+
 export const btoaUniversal = (b: ArrayBuffer): string =>
-  isBrowser ? btoa(String.fromCharCode.apply(null, b as any)) : Buffer.from(b).toString('base64');
+  isBrowser ? btoa(arrayBufferToString(b)) : Buffer.from(b).toString('base64');
 
 export function randomIntFromInterval(min: number, max: number) {
   return Math.floor(Math.random() * (max - min + 1) + min);
@@ -42,3 +48,31 @@ export function compressProgram(jsonProgram: Program | string): CompressedProgra
   const base64 = btoaUniversal(compressedProgram);
   return base64;
 }
+
+function buf2hex(buffer: Uint8Array) {
+  return [...buffer].map((x) => x.toString(16).padStart(2, '0')).join('');
+}
+
+const keccakHex = (value: string): string => buf2hex(keccak256(stringToUint8Array(value)));
+
+/**
+ * Function to get the starknet keccak hash from a string
+ *
+ * [Reference](https://github.com/starkware-libs/cairo-lang/blob/master/src/starkware/starknet/public/abi.py#L17-L22)
+ * @param value - string you want to get the starknetKeccak hash from
+ * @returns starknet keccak hash as hex string
+ */
+export function starknetKeccak(value: string): string {
+  return `0x${keccakHex(value).substr(2)}`;
+}
+
+/**
+ * Function to get the hex selector from a given function name
+ *
+ * [Reference](https://github.com/starkware-libs/cairo-lang/blob/master/src/starkware/starknet/public/abi.py#L25-L26)
+ * @param funcName - selectors abi function name
+ * @returns hex selector of given abi function name
+ */
+export function getSelectorFromName(funcName: string) {
+  return starknetKeccak(funcName);
+}

src/utils.ts

@@ -57,7 +57,7 @@
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
     // "importsNotUsedAsValues": "remove",               /* Specify emit/checking behavior for imports that are only used for types */
-    // "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
+    "downlevelIteration": true /* Emit more compliant, but verbose and less performant JavaScript for iteration. */,
     // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
     // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
     // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */